GNSS Introduction

LTE AT

LTE AT System

GNSS-Standalone Mode

Customers can get useful information about SIM7500/SIM7600 GNSS/A-GNSS functions quickly through this document.

GNSS function could be easily realized by AT command interface provided in SIM7500/SIM7600 module via USB interface.

1. SIM7500/SIM7600 GNSS features

♦ Support GPS, GLONASS, BEIDOU, GALILEO, and QZSS satellite systems.

♦ Support standalone mode, MS-based mode, MS-assisted, and XTRA mode

♦ Support cold start and hot start.

♦ Support a subset of the NMEA-0183 standard.

♦ Support NMEA sentences output in NMEA port port.

♦ A-GNSS supports UP (user plane) and CP (control plane) method.

♦ MS-assisted mode supports single fixed; MS-based mode supports seriate fixed.

♦ Support certificate if necessary.

♦ Supporting GNSS starts automatically when module powers on, it supports standalone mode only

2. GNSS Mode Introduction

GNSS Mode	Description
Standalone Mode	Process: Demodulate GNSS data by Module → Calculation of Position by Module the handset demodulates the data directly from the GNSS satellites. This mode has some reduced cold-start sensitivity, and a longer time to first fix as compared to the assisted modes. However, it requires no server interaction and works out of network coverage. Default use GPS, GLONSS, BEIDOU, can use AT+CGNSSMODE set.
MS-assisted Mode	Process: Sending Aiding Data by Server → Sending Code Phases by Module → Calculation of Position by Server When a request for position location is issued, available network information is provided to the location server and assistance is requested from the location server. The location server sends the assistance information to the handset. The handset/mobile unit measures the GNSS observables and provides the GNSS measurements along with available network data (that is appropriate for the given air interface technology) to the location server. The location server then calculates the position location and returns results to the requesting entity.
MS-based Mode	Process: Sending Aiding Data by Server → Calculation of Position by Module The assistant data provided by the location server encompasses not only the information required to assist the handset in measuring the satellite signals, but also the information required to calculate the handset’s position. Therefore, rather than providing the GNSS measurements and available network data back to the location server, the mobile calculates the location on the handset and passes the result to the requesting entity.